dressel

# Goals: minimize calls to ordered_states (allocates memory)

# needs pomdp for state_index in pdf(b, s)
# needs list of ordered_states for rand(b)
mutable struct DiscreteBelief{P<:POMDP, S}
    pomdp::P
    state_list::Vector{S}       # vector of ordered states
    b::vector{Float64}
end